Success in work does not make one happy, or at least in the long run does not do so. It has been discussed in great detail in book The Power of Now if I rememb

Success in work does not make one happy, or at least in the long run does not do so. It has been discussed in great detail in book The Power of Now if I remember correctly, that there are two types of happiness, pleasure and joy. Pleasure is short-term and results usually from external events. Winning a lottery, having a party, making your first million, and etc, these will bring great pleasure to you. However, pleasure fades away fast, and you will not feel any difference after some time, no matter a day, week, or a month. The life goes on, and you still have all other things to make you stressed and feel miserable. This is why people say money cannot make one happy. Joy is, on the contrary a skill that can be learnt. It is an attitude to be content with your current state, and be just a little bit above that "neutral" mood, no matter in what adversity. With this skill, you would not worry about if you would succeed in your job, because it is irrelevant to your happiness. Both The Power of Now and Stoicism stuff like A Guide to the Good Life: The Ancient Art of Stoic Joy can give you some hints on how to live a joyful life.